Another reason why I want to know more precisely the wind force is the fact that I have rather (perhaps too) many sail sizes.
I mean, probably I would not be using an anemometer if I had only 3 sails, say 5.5, 7.0 and 8.5, which probably would also cover most of the wind range. In this case the scale of Beaufort would probably also be sufficient: F4,5,6. Never a dillemma, no worries.
But my sail range is: 5.0,5.7,6.7,7.8,8.8,11.0 and I want to have the ideal setup for a given wind force.
When I arrive at my favourite spot, the first thing I do is a wind speed measurement. I've got a windmaster 2 and I'm really happy with it. It indicates the current, average and max wind speed. I'm only interested in the average wind speed of course. Then I do some other things that keep me busy with everthing BUT rigging up the sail, because I want to postpone this as long as possible. E.g. I take out the board of the trailer, screw the fin, take out the boom, mast, sailbag, go to the toilets, etc..
The reason of this, is that I want to confirm my measurement, let's say 15 minutes later. If I get confirmation of approximately the same measurement as before (always average wind speed), I will rig up my sail accordingly. If there is too much difference, probably I will put on my neoprene first and do still a 3rd measurement afterwards. If this is again completely different, I get nuts
Then probably I will go to others to see and ask what they rig, I really hate to do this because then everything gets so subjective ...
Luckily, most of the times, I get after three measurements a really good indication.
I guess that all of this sounds a little bit freaky, but I know that I'm not the only one.
Oh yes, and there is also the psychological aspect of picking the sail size.
Only recently, when I was about to rig my sail, I saw an old windsurf buddy on the beach with all brand new slalom stuff.
I changed my sail for 1 size up. Why ? I just knew he was going to show off and do some fun drag racing with me. Too much testosteron, I know. Stupid, because afterwards I was too overpowered.
Another example is when I feel a little tired, I sometimes tend to rig 1 sail size smaller which I afterwards regret.
You see, picking a sail size can be one of the hardest things about windsurfing unless you stick to objective measurements.